b 1. Field of the Invention
The invention relates to an improved apparatus and method for document and copy sheet handling in copy machines and other reproduction equipment.
2. Description of the Related Art
During normal operation of conventional copy machines as with the present invention, while a document is being scanned at a scanning station, the image of a previous document on a photoreceptor is simultaneously processed.
As shown in FIG. 3, a document N is scanned on a platen and its image is recorded as a latent image on a photoreceptor (P/R) during a first time period T1. Subsequently, during period T2, a copy sheet N leaves a paper tray and begins traveling towards a transfer station where the image of document N will be transferred to the copy sheet. Also during the time period T2, documents N is replaced by a subsequent document N+1 on the platen.
During time period T3, is the latent image of document N on the photoreceptor is developed at a developing station, while document N+1 is simultaneously scanned on the platen. During time period T4, developed image N on the photoreceptor is transferred to copy sheet N at the transfer station, copy sheet N+1 leaves the paper tray, and latent image N+1 on the photoreceptor is developed. Additionally, document N+2 is scanned on the platen during time period T4.
Finally, during time period T5, image N is cleaned from the photoreceptor at a cleaning station and the photoreceptor is recharged at a recharge station. Simultaneously, developed image N+1 is transferred to copy sheet N+1 at the transfer station, and copy sheet N+2 leaves the paper tray.
The above described sequence, which is typically controlled by a controller within the copy machine, maximizes the efficiency and speed of the machine. However, when a copy paper misfeed occurs in the conventional copy machine, the efficiency of the copy machine suffers greatly.
As depicted in FIG. 4, in a conventional copy machine, when, after document N is replaced by document N+1 on the platen, a copy sheet misfeed occurs, the latent image on the photoreceptor belt is developed with toner. However, since a misfeed has occured in the paper path for supplying the transfer station with copy paper, the developed toner image cannot be transferred to a copy sheet and is therefore cleaned from the photoreceptor belt at the cleaning station. After the paper jam is cleared, the document handler must recirculate all of the documents until documents N reappears on the platen for rescanning.
The conventional copy machine misfeed algorithm is inefficient in three respects. First, it requires the document handler to recirculate the entire set of documents to return the "N" document to the platen. This can be very time consuming especially when a large stack of documents is in the document handler. Second, it requires that the N document be scanned twice, a first time before the misfeed and second time after the misfeed. Third, it requires that the initial developed image of the N document be cleaned from the photoreceptor at a cleaning station. This cleaning contaminates the cleaning station with a large quantity of unused toner. During usual cleaning after image transfer, only about 5% of the toner remains on the photoreceptor belt for cleaning. However, when transfer of the developed image does not occur, nearly 100% of the toned image must be cleaned off of the photoreceptor belt at the cleaning station. This excess toner contaminates the cleaning station and shortens its life.
The objects of the present invention are to provide a method and apparatus for document handling that is more efficient than the apparatus and methods of the prior art.
It is also an object of the present invention to provide a method and apparatus that obviates the need to scan a document twice when a copy sheet misfeed occurs.
It is a further object of the present invention to provide a method and apparatus that does not contaminate the cleaning station with excess toner when a copy sheet misfeed occurs.
It is also an object of the present invention to provide a method and apparatus that does not require the document handler to recirculate an entire set of documents after a copy sheet misfeed.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description and may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.